Description

GPR44, also called CRTH2, is a Prostanoid Receptor that binds prostaglandin D2. PGD2 signals through CRTH2 to induce Th2, eosinophil, and basophil chemotaxis in a G-alpha(i) dependent manner. CRTH2 may play a role in mast cell-mediated immune responses such as those involved in allergic reactions. This receptor is upregulated in activated T helper-2 (Th2) cells, peripheral blood basophils, and eosinophils, but not in Th1 lineage cells. It may be a useful marker for Th2 and Tc2 cells. CRTH2 has been reported to be expressed in the central nervous system, peripheral tissues, and in blood cells, particularly activated T helper-2 cells. Two transcripts have been isolated, a 3.5-kb transcript expressed primarily in the thalamus, frontal cortex, pons, and hippocampus, and a 3.4-kb transcript expressed in fetal liver, leukocytes, and thymus. ESTs have been isolated from B-cell/lung/testis, brain, kidney, liver/spleen, placenta, prostate, testis, and thymus libraries.